Explanation

The disease caused by congenital deficiency of thyroxine is Cretinism.

Cretinism is a condition that occurs due to inadequate thyroid hormone production or action, particularly during fetal development or infancy.

Thyroxine, also known as T4, is essential for normal growth and development, including:

• brain development
• Congenital hypothyroidism

Cretinism is characterized by severe:

• physical and mental retardation
• stunted growth
• other developmental abnormalities

Explanation

The two unpaired facial bones are the mandible and the vomer.

Mandible:

The mandible, commonly known as the jawbone, is the largest and strongest bone of the face.

It forms the lower jaw and holds the lower teeth in place.

It is the only movable bone of the skull.

Vomer:

The vomer is a thin, flat bone that forms part of the nasal septum, which divides the nasal cavity into left and right sides.

It is located inferiorly within the nasal cavity.

Explanation

Spondylosis affects the vertebral joints.

Spondylosis is a term used to describe degenerative changes in the spine

Particularly in the vertebral joints and intervertebral discs.

It involves the breakdown of the cartilage and the formation of bone spurs in the spine

Which can lead to pain, stiffness, and decreased mobility. 

Explanation

Meissner corpuscles provide sensation about touch, while Pacinian corpuscles provide sensation about pressure.

Meissner corpuscles are found in the dermal papillae of the skin and are sensitive to light touch and vibration.

They are particularly concentrated in areas such as the fingertips, lips, and palms.

Pacinian corpuscles are found deeper in the skin and are sensitive to deep pressure and high-frequency vibration.

They are responsible for detecting mechanical stimuli such as pressure and vibration.

Explanation

Annelids do have a closed circulatory system, along with other invertebrates and vertebrates

Annelids, like earthworms, have a closed circulatory system.

In annelids, blood is pumped along by muscles in blood vessels.

The blood picks up food molecules from the digestive tract and oxygen from the skin.

It then transports these to the cells of the body. 

Explanation

• Under normal resting conditions, 100 ml of venous blood contains approximately 52 ml of CO₂.
• For comparison:
• Venous blood: ~52 ml CO₂ / 100 ml blood
• Arterial blood: ~48 ml CO₂ / 100 ml blood
• The difference occurs because tissues add CO₂ to the blood before it returns to the heart through veins.

Explanation

Instead of alveoli, birds (aves) have parabronchi.

Parabronchi are the structures in the avian respiratory system

They are the site of gas exchange, where oxygen from the air is absorbed into the bloodstream and carbon dioxide is released from the bloodstream into the air.

Birds have a unique respiratory system that includes air sacs connected to their lungs. 

Parabronchi are the functional units where gas exchange occurs within the avian respiratory system.

Explanation

Enterokinase, also known as enteropeptidase, is an enzyme produced by cells lining the duodenum in the small intestine.

It plays a crucial role in the digestion of proteins by activating trypsinogen, an inactive precursor of trypsin.

Once trypsinogen is activated by enterokinase,

it can then activate other pancreatic zymogens and initiate the digestion of proteins in the small intestine.

Explanation

Carotenoids serve multiple functions in plants:

Broaden Spectrum of Light:

• Carotenoids can absorb light energy in the blue and green regions of the spectrum,
• thereby expanding the range of light wavelengths that can be used for photosynthesis.

Provide Yellow Color to the Plants:

• Carotenoids are responsible for the yellow, orange, and red colors observed in many fruits, flowers, and vegetables.

Protect Chlorophyll by Absorbing Excessive Light:

• Carotenoids act as photoprotective agents by dissipating excess energy that chlorophyll molecules cannot handle,
• thus protecting the photosynthetic machinery from damage caused by excessive light exposure.

Explanation

The dark reactions of photosynthesis occur in the stroma (aqueous fluid surrounding the stacks of thylakoids) of the chloroplast

Where they utilize the products of the light reaction.

In the dark reaction, plants use carbon dioxide with ATP and NADPH from the light reactions to produce glucose.